The field of this invention is in the electronic countermeasures art.
The desirability of adding range gate deception to an ECM system is well understood and particularly the desirability of range gate deception means that will not require shutting off the receiver of the system with the resulting dead time in the repeater capability. Prior to this invention this has been only partially accomplished and then only in a limited and essentially impractical way. The prior art repeaters with range gate deception have attempted to achieve a broadened pulse by using a coaxial line delay means. The operating systems have had coaxial delay lines approximately 130 feet long and these lines provided a delay of only 0.15 microsecond. These systems required that the receiver be shut off after the 0.15 microsecond of delay to prevent interference when the wave is reinforced. Making the coaxial line longer to provide greater delay has been prohibitive because of line loss. Using the 0.15 microsecond delay causes the repeated radio frequency signal to be spread and cover a spectrum of approximately 6.7 megacycles of RF frequencies. This is wider than the (opposing) radar receiver bandwidth and, as a result, much of the jammer energy is not effective. The requirement of having to shut off the receiver after the 0.15 microsecond additionally causes the jammer to not repeat a pulse that is delayed with respect to the first pulse by 0.15 microsecond or more.
To further explain by example this deficiency of prior systems using a coaxial line delay means; assume a system has a delay of 0.15 microsecond in the coaxial line in the feedback loop to widen a received radar pulse; the typical received pulse has a width of 0.5 microsecond, then the delayed pulse will be fed back into the system while the received pulse is still coming in. Thus, the received energy must be shut off to the repeater system after 0.15 microsecond (to prevent interference and cancellation) to allow the feed-back loop to ring providing a pulse (by the successive ringing) that is wider than the original received pulse signal.